Method for manufacturing a lower substrate of a liquid crystal display device

ABSTRACT

A method for manufacturing a lower substrate of a liquid crystal display device is disclosed and more particularly, a method for manufacturing a color filter layer on a lower substrate is disclosed. This method is achieved by using a photosensitive insulating layer as a passivation layer or an overcoat of a thin film transistor to reduce the number of masks, or of photographic steps. The photosensitive insulating layer used in the method has the characteristics of both photoresist and passivation layers so as to protect a thin film transistor from moisture and oxygen. In addition, the number of masks, or of photographic steps used in this method can be further reduced by ink-jet printing a color filter layer or by half-tone mask technique.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a thin filmtransistor array substrate of a liquid crystal display device, and moreparticularly, to a method for manufacturing a color filter layer on athin film transistor array substrate.

2. Description of Related Art

A thin film transistor liquid crystal display (TFT-LCD) mainly comprisesa thin film transistor (TFT) array substrate, a color filter substrateand a liquid crystal layer sandwiched therebetween. The TFT arraysubstrate comprises plural pixels in an array, each of which comprises aTFT and a pixel electrode electrically connected to the TFT. Generally,the aperture ratio of a single pixel in the TFT-LCD device directlyrelates to the quantity of light passing through transparent areas fromback light modules. For the TFT-LCD devices having the same powerconsumption, a higher aperture ratio means a better brightness ofTFT-LCD devices.

However, in the process for assembling the TFT array substrate and thecolor filter substrate, since in practice the black matrix, quite often,cannot align with the color filter accurately, the resulting alignmentshift usually causes leakage of light. Hence, in the conventionalprocess for manufacturing a TFT array substrate of an LCD device, theblack matrix is designed to be broader than the desired area to beblocked so as to completely inhibit the leakage. However, the apertureratio of the LCD device is thereby reduced.

In order to obviate the aforementioned problems, a COA (color filter onarray) technology has been developed. A COA-TFT substrate of a LCDdevice is provided to enhance the aperture ratio, and the resolution aswell.

FIGS. 1A to 1G are cross-section views of a conventional method formanufacturing a COA-TFT by nine photographic steps. As shown in FIG. 1A,a first metal layer 102 is first formed on a substrate 101 bysputtering, and a gate and other elements of a transistor are defined.Subsequently, as shown in FIG. 1B, SiNx or SiOx as a gate insulatinglayer 103, a-Si as a semiconductor layer 104, and n⁺Si as an ohmiccontact layer 105 are formed by PECVD, and then a patterned activeregion is formed by a photographic step. Then, as shown in FIG. 1C,Ti/Al/Ti or Ti/Al as a second metal layer 106 is formed by sputtering, asource and a drain are defined by a photographic step, and the ohmiccontact layer 105 is etched to form a through hole by dry etching. Asshown in FIG. 1D, SiNx or SiOx as a passivation layer 107 is formed bychemical vapor deposition. Subsequently, a patterned black matrix 108 isformed by coating a photosensitive black resin layer, pre-baking, andthen a photographic step.

After the above process, a red filter layer 109 and a contact hole 110are formed simultaneously by coating a photosensitive red resin layer,pre-baking, and then a photographic step. Subsequently, a green filterlayer 111 in the green pixel region, a blue filter layer (not shown) inthe blue pixel region, and the contact holes thereof (not shown) areformed by repeating the process for preparing the red pixel region, asthe structure in FIG. 1E. Then, an overcoat 112 and a photoresist (notshown) are formed in sequence by coating, and then a contact hole 113 isformed by a photographic process, as the structure shown in FIG. 1F.Finally, as shown in FIG. 1G, a transparent electrode layer 114 isformed by plating, and a patterned pixel region is defined by aphotographic step to accomplish the process for preparing a COA-TFT.

As the aforementioned illustration, the conventional process formanufacturing a COA-TFT includes five photographic steps for preparing aTFT array substrate and four photographic steps for preparing a colorfilter substrate (a total of nine photographic steps). Distinctly, theprocess for manufacturing a COA-TFT can enhance the aperture ratio, butthe complex photographic steps would reduce the yield throughout.

Thereby, in order to reduce the manufacturing cost, and to enhance theyield and the stability of the products, how to simplify thephotographic process for preparing a COA-TFT becomes an important issue.

SUMMARY OF THE INVENTION

The present invention takes a photosensitive insulating layer as apassivation layer or an overcoat of a TFT to reduce the number of masksor simplify the manufacturing process. In addition, the number of masksor the manufacturing process is further reduced or simplified by atechnique of ink-jet printing in forming a color filter layer orhalf-tone mask.

The present invention provides a process for manufacturing a lowersubstrate of an LCD device, comprising: (A) providing a substrate; (B)forming plural transistors each comprising a gate, a source, and adrain, wherein the gate is on substrate, at least one semiconductorlayer and at least one gate insulating layer are sandwiched in betweenthe gate and the source/drain, and the drain does not electricallyconnect to the source; (C) forming on the substrate in sequence a firstphotosensitive insulating layer and a black matrix, wherein the firstinsulating layer and the black matrix are both positive photoresists ornegative photoresists; (D) patterning the first photosensitiveinsulating layer and the black matrix to cover the transistor regions,wherein the pattern of the first photosensitive insulating layer is thesame as that of the black matrix; (E) forming on the substrate insequence a second photosensitive insulating layer and a color filterlayer, wherein the second photosensitive insulating layer and the colorfilter layer are both positive photoresists or negative photoresists;(F) patterning the second photosensitive insulating layer and the colorfilter layer, and simultaneously forming a first contact hole in thesecond photosensitive insulating layer and the color filter layer on thedrain, wherein the first contact layer extends through the secondphotosensitive insulating layer and the color filter layer to expose thepart drain; (G) selectively repeating the steps (E) and (F); and (H)forming on the substrate a patterned transparent electrode layer whichelectrically connects to the drain.

The first photosensitive insulating layer and the black matrix used inthe process for preparing a lower substrate of an LCD device must beboth positive photoresists or negative photoresists so as to patternthem simultaneously by a photographic step. In addition, the colorfilter layer and the second photosensitive insulating layer must alsotogether be positive photoresists or negative photoresists so as topattern them simultaneously by a photographic step, and that thephotographic process can thereby be simplified.

The materials of the first and second photosensitive insulating layersof the present invention can be any photosensitive materials which canfunction as a passivation layer of the TFT so as to efficiently protectthe TFT from moisture or oxygen in air. Preferably, the materials of thefirst and second photosensitive insulating layers are the materialscontaining major Si, and organic or inorganic matter to exhibit anexcellent insulation property and an excellent transmittance property,and a function of development as general photoresists. More preferably,the materials of the first and second photosensitive insulating layersare the materials containing organic silsesquioxane (OSQ).

The drain of the present invention comprises a drain electrode and adrain line, and the drain line is a metal line extending from the drainelectrode. The drain line can electrically connect the drain and thepixel electrode. If the lower substrate of the LCD device of the presentinvention contains an auxiliary capacitance, the drain line can functionas the upper electrode of the auxiliary capacitance.

The structure of the gate of the present invention can be asingle-layered structure or a multi-layered structure. Preferably, thestructure of the gate is a single-layered structure of aluminum,tungsten, chromium, titanium, TiNx, aluminum alloy, chromium alloy,molybdenum, or a combination thereof, or a multi-layered structurecomprising the aforementioned single-layered metal layer and aheat-resistant metal layer (such as Cr

Ta

Ti

MoW or an alloy thereof).

The drain and the source of the present invention can be single-layeredor multi-layered metal layers. Preferably, the drain and the source aresingle-layered structures of aluminum, tungsten, chromium, titanium,TiNx, aluminum alloy, chromium alloy, molybdenum, or a combinationthereof, or multi-layered structures comprising a heat-resistant metallayer (such as Cr

Ta

Mo), a wiring layer with low resistance (such as Al), and a middleconductive layer (such as Ti). More preferably, the drain and the sourceare multi-layered metal layers of Ti/Al/Ti or Ti/Al.

According to the present invention, the material of the semiconductorlayer is not limited. Preferably, the material is an amorphous siliconmaterial, or a polymorphous silicon material.

The gate insulating layer can suitably be of any insulation material.Preferably, the material is an organic material, an inorganic material,or the combination thereof. More preferably, the material is SiO₂, SiNx,Si(OH)₄, or the combination thereof.

The transparent electrode layer can suitably be of any transparent andconductive material. Preferably, the material is ITO, IZO, or ITZO.

In addition, according to the present invention, the colors of the colorfilter layers each corresponding to one TFT on the lower substrate of anLCD device can be the same or different. Preferably, the colors of thecolor filter layers neighboring with each other are different.

Furthermore, in addition to fabricating TFTs on the substrate, theprocess for manufacturing a lower substrate of an LCD device can furthercomprise a step for fabricating a connecting terminal region, or anauxiliary capacitance region on the substrate to provide a completelower substrate of a TFT-LCD device.

As the aforementioned process, the present invention provides a firstpreferred embodiment to form a transistor region and a connectingterminal region on the substrate of an LCD device. The process of thefirst preferred embodiment of the present invention comprises thefollowing steps: (A) providing a substrate; (B) forming pluraltransistor regions each comprising a gate, a source, and a drain, andsimultaneously forming plural connecting terminal regions individuallycomprising at least one terminal line on the substrate, wherein the gateis on the surface of the substrate, at least one semiconductor layer andat least one gate insulating layer are sandwiched in between the gateand the source/drain, the drain does not electrically connect to thesource, and the gate insulating layer is on the terminal line; (C) afirst photosensitive insulating layer and a black matrix are formed onthe substrate in sequence, wherein the first photosensitive insulatinglayer and the black matrix together are positive photoresists ornegative photoresists; (D) patterning the first photosensitiveinsulating layer and the black matrix to cover the transistor regions,wherein the pattern of the first photosensitive insulating layer is thesame as that of the black matrix; (E) a second photosensitive insulatinglayer and a color filter layer are formed on the substrate in sequence,wherein the second photosensitive insulating layer and the filter layertogether are positive photoresists or negative photoresists; (F)patterning the second insulating layer and the color filter layer,simultaneously forming a first contact hole in the second insulatinglayer and the color filter layer on the drain, and a second contact holein the connecting terminal region, wherein the first contact holeextends through the second photosensitive insulating layer and the colorfilter layer to expose the part drain, and the second contact hole atleast extends through the second photosensitive insulating layer toexpose the part gate insulating layer; (G) selectively repeating thesteps (E) and (F); (G′) dry etching the exposed gate insulating layer toexpose the part terminal line; and (H) forming a patterned transparentelectrode layer on the substrate, which electrically connects to thedrain.

The present invention further provides a second preferred embodiment toform a transistor region and a connecting terminal region on thesubstrate. The process of the second preferred embodiment comprises thefollowing steps: (A) providing a substrate; (B) forming pluraltransistor regions each comprising a gate, a source, and a drain, andsimultaneously forming plural connecting terminal regions on thesubstrate, individually comprising at least one terminal line and atleast one connecting line, wherein the gate and the terminal line are onthe substrate, at least one semiconductor layer and at least one gateinsulating layer are sandwiched in between the gate and thesource/drain, the drain does not electrically connect to the source, thegate insulating layer is sandwiched in between the terminal line and theconnecting line, and the connecting line connects to the terminal linevia a through hole; (C) forming on the substrate in sequence a firstphotosensitive insulating layer and a black matrix, wherein both theinsulating layer and the black matrix are positive photoresists ornegative photoresists; (D) patterning the first photosensitiveinsulating layer and the black matrix to cover the transistor regions,wherein the pattern of the first photosensitive insulating layer is thesame as that of the black matrix; (E) forming a second photosensitiveinsulating layer and a color filter layer on the substrate in sequence,wherein the second photosensitive insulating layer and the color filterlayer together are positive photoresists or negative photoresists; (F)patterning the second photosensitive insulating layer and the colorfilter layer, simultaneously forming a first contact hole in the secondphotosensitive insulating layer and the color filter layer on the drain,and a second contact hole in the connecting terminal region, wherein thefirst contact hole extends through the second photosensitive insulatinglayer and the color filter layer to expose the part drain, and thesecond contact hole at least extends through the second photosensitiveinsulating layer to expose the part connecting line; (G) selectivelyrepeating the steps (E) and (F); and (H) forming on the substrate apatterned transparent electrode layer which electrically connects to thedrain.

The present invention further provides a third embodiment to form atransistor region and an auxiliary capacitance region on the substrateof an LCD device. The process of the third embodiment of the presentinvention is similar to the aforementioned process. However, in step(B), plural auxiliary capacitance regions each at least comprising alower electrode, a gate insulating layer, and an upper electrode areformed on the substrate. The lower electrode is on the substrate, andthe gate insulating layer is sandwiched in between the upper electrodeand the lower electrode.

In addition, according to the present invention, the process forpatterning the first photosensitive insulating layer and the blackmatrix, as described in step (D), is not limited. Preferably, theprocess for patterning the first photosensitive insulating layer and theblack matrix is performed by a mask, exposure, and development. Theprocess for forming the color filter layer of the step (F) is notlimited. Preferably, the process is spin coating or ink-jet printing.

In addition to the aforementioned process, the present invention furtherprovides another process for manufacturing a lower substrate of an LCDdevice to take a nonphotosensitive insulating layer as a passivationlayer of the TFT, and a photosensitive insulating layer as an overcoatof the TFT to simplify the photographic process. The process comprisesthe following steps: (A) providing a substrate; (B) forming pluraltransistor regions each having a gate, a source, and a drain, whereinthe gate is on the substrate, at least one semiconductor layer and atleast one gate insulating layer are sandwiched in between the gate andthe source/drain, and the drain does not electrically connect to thesource; (C) forming a passivation layer, a black matrix, and a firstphotosensitive insulating layer on the substrate in sequence; (D)patterning the first photosensitive insulating layer and the blackmatrix to cover the transistor regions, wherein the pattern of the firstphotosensitive insulating layer is the same as that of the black matrix;(E) forming on the substrate in sequence a second photosensitiveinsulating layer and a color filter layer; (F) patterning the secondphotosensitive insulating layer and the color filter layer, and forminga first contact hole both in the second photosensitive insulating layerand the color filter layer on the drain, wherein the first contact holeextends through the second photosensitive insulating layer and the colorfilter layer to expose the part passivation layer; (G) selectivelyrepeating the steps (E) and (F); (H) dry etching the passivation layerin the first contact hole to expose the part drain; and (I) forming onthe substrate a patterned transparent electrode layer which electricallyconnects to the drain.

The drain of the present invention comprises a drain electrode and adrain line, and the drain line is a metal line extending from the drainelectrode. The drain line can electrically connect the drain and thepixel electrode. If the lower substrate of an LCD device of the presentinvention contains an auxiliary capacitance, the drain line can functionas an upper electrode of the auxiliary capacitance. The colors of thecolor filter layers, each corresponding to one TFT on the lowersubstrate of an LCD device, can be the same or different. Preferably,the colors of the color filter layers neighboring with each other aredifferent.

In addition to fabricating TFTs on the substrate, the process formanufacturing a lower substrate of an LCD device can further comprise astep of fabricating on the substrate a connecting terminal region, or anauxiliary capacitance region so as to provide a complete lower substrateof a TFT-LCD device.

The present invention further provides a fourth embodiment to form aconnecting terminal region on the substrate of an LCD device. Theprocess of the fourth embodiment is similar to the aforementionedprocess. However, in step (B), plural connecting terminal regions, atleast each comprising a terminal line, are formed on the substrate. Theterminal line is on the substrate, and the gate insulating layer issandwiched in between the terminal line and the passivation layer. Step(F) further comprises a step for simultaneously forming a second contacthole in the second photosensitive insulating layer and the color filterlayer in each connecting terminal region. The second contact holeextends through the second photosensitive insulating layer and the colorfilter layer so as to expose part of the passivation layer. Step (H)further comprises a step for dry etching the passivation layer and thegate insulating layer in the second contact hole so as to expose part ofthe terminal line and to thereby form contact holes of the connectingterminal regions.

The present invention further provides a fifth embodiment to form anauxiliary capacitance region on the substrate of an LCD device. Theprocess of the fifth embodiment of the present invention is similar tothe aforementioned process. However, in step (B), plural auxiliarycapacitance regions, at least each comprising a lower electrode, a gateinsulating layer, and an upper electrode, are formed on the substrate.The lower electrode is on the substrate, and the gate insulating layeris sandwiched in between the upper electrode and the lower electrode.

In addition, the process for patterning the first photosensitiveinsulating layer and the black matrix of the step (D) is not limited.Preferably, the process for patterning the first photosensitiveinsulating layer and the black matrix is performed by a mask, exposure,and development. The process for forming the color filter layer of step(F) is not limited. Preferably, the process is spin coating or ink-jetprinting.

Other objects, advantages, and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1G are cross-sectional views according to a conventionalmanufacturing method;

FIGS. 2A to 2G are cross-sectional views illustrating a manufacturingmethod according to a first embodiment of the present invention;

FIGS. 3A to 3G are cross-sectional views illustrating a manufacturingmethod of a second embodiment according to the present invention;

FIGS. 4A to 4F are cross-sectional views illustrating a manufacturingmethod according to a third embodiment of the present invention;

FIGS. 5A to 5D are cross-sectional views illustrating a manufacturingmethod according to a fourth embodiment of the present invention; and

FIGS. 6A to 6D are cross-sectional views illustrating a manufacturingmethod according to a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiment 1

The present embodiment uses a photosensitive insulating layer as apassivation layer or an overcoat of the TFT so as to reduce thephotographic steps by one.

Please refer to FIGS. 2A to 2G, wherein cross-sectional views illustratethe process for manufacturing a lower substrate of an LCD device of thepresent embodiment.

A first metal layer (not shown) is first formed on a substrate 201 bysputtering, and a gate 202 in the thin film transistor region A, a lowerelectrode 203 in the auxiliary capacitance region, and a terminal line204 in the connecting terminal region are defined. Subsequently, a gateinsulating layer 205 (SiNx) is formed by PECVD. Then, a semiconductorlayer 208 (a-Si) and an ohmic contact layer 222 (n⁺Si) are formed bydepositing, and then the semiconductor layer 208 and the ohmic contactlayer 222 are patterned to form an active region. Subsequently, a secondmetal layer (not shown) of a Ti/Al/Ti multi-layered structure is formedby sputtering, and the second metal layer is patterned by exposure anddevelopment so as to form a source 209 and the drain 210 in the thinfilm transistor region A, an upper electrode 211 in the auxiliarycapacitance region B, and a connecting line 212 in the connectingterminal region C. The Ti/Al/Ti multi-layered structure of the secondmetal layer is a three-layered structure so as to avoid etching thesecond metal layer for the developer used in the following process.Then, a through hole in the ohmic contact layer 222 is formed by dryetching, as the structure shown in FIG. 2A. In addition to Ti as abarrier layer (not shown in) on the second metal layer of the Ti/Al/Timulti-layered structure, any material which can avoid etching the secondmetal layer for the developer (such as Mo, Cr, Ag and other metals whichcan avoid etching the second metal layer for the developer) can alsofunction as a barrier layer. The upper electrode 211 in the auxiliarycapacitance region B of the present embodiment is the metal lineextending from the drain 210. Thereby, the drain 210 comprises a drainelectrode and a drain line, and the drain line is a metal line extendingfrom the drain electrode. The drain line can electrically connect thedrain 210 and the pixel electrode (not shown), and function as well asan upper electrode 211 of the auxiliary capacitance region B.

Subsequently, a first negative photosensitive insulating layer 213 isformed by coating and then by pre-baking. Then, a negativephotosensitive black resin layer 214 is formed by coating and then bypre-baking, as shown in FIG. 2B. As shown in FIG. 2C, a mask is used forperforming a photographic step to pattern the first negativephotosensitive insulating layer 213 and the negative photosensitiveblack resin layer 214 so as to form a region blocking light. Thepatterned first negative photosensitive insulating layer 213 functionsas a passivation layer of the TFT, and that the patterned negativephotosensitive black resin layer 214 functions as the black matrix ofthe TFT.

A second negative photosensitive insulating layer 215 is formed bycoating and then by pre-baking. Then, a negative red filter layer 216 isformed by coating and then by pre-baking, as shown in FIG. 2D.

As shown in FIG. 2E, the negative red filter layer 216 and the secondnegative photosensitive insulating layer 215 are patterned by exposureand development, and a first contact hole 217 in the negative red filterlayer 216 and a second contact hole 218 in the connecting terminalregion C are formed. The first contact hole 217 of the presentembodiment corresponds to the drain 210 and extends through the secondnegative photosensitive insulating layer 215 and the negative red filterlayer 216 to expose the part drain 210. The second contact hole 218 isdisposed in the connecting terminal region C, and extends through thesecond negative photosensitive insulating layer 215 and the negative redfilter layer 216 so as to expose part of the gate insulating layer 205.

Subsequently, a green filter layer 219 is defined by repeating the stepsof FIGS. 2D to 2E, and then a blue filter layer (not shown) is definedby repeating the steps illustrating in FIGS. 2D to 2E. Each pixel regionof the present embodiment comprises a color filter layer of one color,and the colors of the color filter layers neighboring with each otherare different. The photosensitive black resin layer and all color filterlayers function as masks to dryly etch the gate insulating layer 205 inthe second contact hole 218 in the connecting terminal region C so as toexpose the terminal line 204, as shown in FIG. 2F.

Finally, as shown in FIG. 2G, a transparent electrode layer (ITO) 220 isformed, and the pattern of the pixel region is defined by a photographicstep so as to accomplish the process for manufacturing a lower substrateof an LCD device.

The process for manufacturing a lower substrate of an LCD device of thepresent embodiment comprises eight photographic steps. Thereby, thepresent embodiment reduces the photographic steps by one in comparisonwith the conventional process. In addition, a half-tone mask technologycan further reduce the photographic steps by one in the presentembodiment.

Embodiment 2

The present embodiment uses a photosensitive insulating layer as apassivation layer or an overcoat of the TFT to reduce the photographicsteps by one. In addition, the present embodiment improves the method ofEmbodiment 1 to omit the dry-etching process for a contact hole in theconnecting terminal region C, and to inhibit the issues of reducedthickness of the black matrix and the color filter layer resulting fromion impact.

Please refer to FIGS. 3A to 3G, wherein cross-sectional views illustratethe process for manufacturing a lower substrate of an LCD device of thepresent embodiment.

A first metal layer (not shown) is first formed on a substrate 301 bysputtering, and a gate 302 in the thin film transistor region A, a lowerelectrode 303 in the auxiliary capacitance region B, and a terminal line304 in the connecting terminal region C are defined. As shown in FIG.3B, a gate insulating layer 305 (SiNx) is formed by PECVD. Then, asemiconductor layer 308 (a-Si) and an ohmic contact layer 322 (n⁺Si) areformed by depositing; the semiconductor layer 308, the ohmic contactlayer 322, and the gate insulating layer 305 are dryly etched by aphotographic step; and then a through hole 321 extends through thesemiconductor layer 308, the ohmic contact layer 322, and the gateinsulating layer 305 to expose the terminal line 304 is formed in theconnecting terminal region C. Subsequently, a second metal layer (notshown) of a Ti/Al/Ti multi-layered structure is formed by sputtering,and a photoresist layer (not shown) is coated to perform exposure anddevelopment; and the second metal layer is patterned by wet etching soas to define a source 309 and the drain 310 in the transistor region A,an upper electrode 311 in the auxiliary capacitance region B, and aconnecting line 312 in the connecting terminal region C. The connectingline 312 connects to the terminal line 304 via the through hole 321. TheTi/Al/Ti multi-layered structure of the second metal layer is athree-layered structure so as to avoid etching the second metal layerfor the developer used in the following process. Then, a through hole inthe ohmic contact layer 322 is formed by dry etching, as the structureshown in FIG. 3C. The upper electrode 311 in the auxiliary capacitanceregion B of the present embodiment is a metal line extending from thedrain 310. Thereby, the drain 310 comprises a drain electrode and adrain line, and the drain line is a metal line extending from the drainelectrode. The drain line can electrically connect the drain 310 and thepixel electrode (not shown), and function as well as an upper electrode311 of the auxiliary capacitance region B.

Subsequently, a first negative photosensitive insulating layer 313 isformed by coating and then by pre-baking. Then, a negativephotosensitive black resin layer 314 is formed by coating and then bypre-baking. As shown in FIG. 3D, a mask is used for performing aphotographic step to pattern the first negative photosensitiveinsulating layer 313 and the negative photosensitive black resin layer314 so as to form a region blocking light. The patterned first negativephotosensitive insulating layer 313 functions as a passivation layer ofthe TFT, and the patterned negative photosensitive black resin layer 314functions as the black matrix of the TFT.

A second negative photosensitive insulating layer 315 is formed bycoating and then by pre-baking. Then, a negative red filter layer 316 isformed by coating and then by pre-baking. Subsequently, the negative redfilter layer 316 and the second negative photosensitive insulating layer315 are patterned by exposure and development, and a first contact hole317 in the negative red filter layer 316 and a second contact hole 318in the connecting terminal region C are formed. The first contact hole317 corresponds to the drain 310, and extends through the secondnegative photosensitive insulating layer 315 and the negative red filterlayer 316 so as to expose part of the drain 310. The second contact hole318 is disposed in the connecting terminal region C, and extends throughthe second negative photosensitive insulating layer 315 and the negativered filter layer 316 so as to expose part of the connecting line 312.

Subsequently, a green filter layer 319 is defined by repeating the stepsof FIG. 3E, and then a blue filter layer (not shown) is defined byrepeating the steps of FIG. 3E. Each pixel region of the presentembodiment comprises a color filter layer of one color, and the colorsof the color filter layers neighboring with each other are different, asshown in FIG. 3F.

Finally, as shown in FIG. 3G, a transparent electrode layer (ITO) 320 isformed, and the pattern of the pixel region is defined by a photographicstep so as to accomplish the process for manufacturing a lower substrateof an LCD device.

The process for manufacturing a lower substrate of an LCD device of thepresent embodiment comprises eight photographic steps. Thephotosensitive insulating layer of the present invention can function asthe passivation layer or the overcoat of the TFT. Thereby, the presentembodiment reduces the photographic steps by one and omits the processfor coating an overcoat, in comparison with the conventional process. Inaddition, a half-tone mask technique can further reduce the photographicsteps by one in the present embodiment.

Embodiment 3

The present embodiment uses a photosensitive insulating layer as apassivation layer or an overcoat of the TFT to reduce the photographicsteps by one. In addition, the present embodiment improves the method ofEmbodiment 1 to further reduce the photographic steps by two via ink-jetprinting so as to form three color filter layers of different colors.The manufacturing steps and the manufacturing cost are reduced due toreducing omitting the number of steps in photosensitive insulating layercoating.

Please refer to FIGS. 4A to 4F, wherein cross-sectional views illustratethe process for manufacturing a lower substrate of an LCD device of thepresent embodiment.

A lower substrate 400 of an LCD device is provided, as shown in FIG. 4A.The process for forming the lower substrate 400 is the same as theprocess for forming the structure of FIG. 2A of Embodiment 1.

Subsequently, a first negative photosensitive insulating layer 413 isformed by coating and then by pre-baking. Then, a negativephotosensitive black resin layer 414 is formed by coating and then bypre-baking, as shown in FIG. 4B. As shown in FIG. 4C, a mask is used forperforming a photographic step in patterning the first negativephotosensitive insulating layer 413 and the negative photosensitiveblack resin layer 414 so as to form a region blocking light. Thepatterned first negative photosensitive insulating layer 413 functionsas a passivation layer of the TFT, and the patterned negativephotosensitive black resin layer 414 functions as the black matrix ofthe TFT.

A second negative photosensitive insulating layer 415 is formed bycoating and then by pre-baking. Then, a red filter layer 416 in the redpixel region, a green filter layer 419 in the green pixel region, and ablue filter layer (not shown) in the blue pixel region are formed byink-jet printing and then by pre-baking, as shown in FIG. 4D. The threecolor filter layers are negative photoresists.

Subsequently, the red filter layer 416, the green filter layer 419, theblue filter layer (not shown), the first contact hole corresponding tothe drain 210, and the second contact hole 418 in the connectingterminal region C are defined by a photographic step. For example, thefirst contact hole 417 corresponds to the drain 210, and extends throughthe red filter layer 416 and the second photosensitive insulating layer415 so as to expose part of the drain 210. The second contact hole 418is disposed in the connecting terminal region C, and extends through thesecond photosensitive insulating layer 415 so as to expose part of thegate insulating layer 205. Then, the black matrix and the color filterlayers function as masks to dryly etch the gate insulating layer 205 inthe second contact hole 418 so as to expose part of the terminal line404, as shown in FIG. 4E.

Finally, as shown in FIG. 4F, a transparent electrode layer (ITO) 420 isformed, and the pattern of the pixel region is defined by a photographicstep so as to accomplish the process for manufacturing a lower substrateof an LCD device.

The process for manufacturing a lower substrate of an LCD device of thepresent embodiment comprises six photographic steps. The photosensitiveinsulating layer of the present invention can function as thepassivation layer or the overcoat of the TFT. Thereby, the presentembodiment reduces the photographic steps by three and omits the stepfor coating an overcoat, in comparison with the conventional process. Inaddition, a half-tone mask technique can further reduce the photographicsteps by one in the present embodiment.

Embodiment 4

The present embodiment uses a photosensitive insulating layer as apassivation layer or an overcoat of the TFT to reduce the photographicsteps by one. In addition, the present embodiment improves the method ofEmbodiment 2 to further reduce the photographic steps by two via ink-jetprinting in forming three color filter layers of different colors. Themanufacturing steps and the manufacturing cost are reduced by omittingthe step for photosensitive insulating layer coating.

Now references to FIGS. 5A to 5D are made, wherein cross-sectional viewsillustrate the process for manufacturing a lower substrate of an LCDdevice of the present embodiment.

A lower substrate 500 of an LCD device is provided, as shown in FIG. 5A.The process for forming the lower substrate 500 is the same as theprocess for forming the structure of FIG. 3C of Embodiment 2.

Subsequently, a first negative photosensitive insulating layer 513 isformed by coating and then by pre-baking. Then, a negativephotosensitive black resin layer 514 is formed by coating and then bypre-baking. As shown in FIG. 5B, a mask is used for performing aphotographic step to pattern the first negative photosensitiveinsulating layer 513 and the negative photosensitive black resin layer514 to form a region blocking light. The patterned first negativephotosensitive insulating layer 513 functions as a passivation layer ofthe TFT, and the patterned negative photosensitive black resin layer 514functions as the black matrix of the TFT.

A second negative photosensitive insulating layer 515 is formed bycoating and then by pre-baking. Then, a red filter layer 516 in the redpixel region, a green filter layer 519 in the green pixel region, and ablue filter layer (not shown) in the blue pixel region are formed byink-jet printing and then by pre-baking. The three filter layers arenegative photoresists. Subsequently, the red filter layer 516, the greenfilter layer 519, the blue filter layer (not shown), the first contacthole corresponding to the drain 310, and the second contact hole 518 inthe connecting terminal region C are defined by a photographic step. Forexample, the first contact hole 517 corresponds to the drain 310, andextends through the red filter layer 516 and the second photosensitiveinsulating layer 515 so as to expose part of the drain 310. The secondcontact hole 518 is disposed in the connecting terminal region C, andextends through the second photosensitive insulating layer 515 so as toexpose part of the connecting line 312, as shown in FIG. 5C.

Finally, as shown in FIG. 5D, a transparent electrode layer (ITO) 520 isformed, and the pattern of the pixel region is defined by a photographicstep so as to accomplish the process for manufacturing a lower substrateof an LCD device.

The process for manufacturing a lower substrate of an LCD device of thepresent embodiment comprises six photographic steps. The photosensitiveinsulating layer of the present invention can function as thepassivation layer or the overcoat of the TFT. Thereby, the presentembodiment reduces the photographic steps by three and omits the stepfor coating an overcoat, in comparison with the conventional process.

Embodiment 5

The present embodiment improves the process for manufacturing a lowersubstrate of an LCD device according to the conventional process (FIGS.1A to 1G) to retain the passivation layer and use a photosensitiveinsulating layer as an overcoat of the TFT so as to reduce thephotographic steps by one. In addition, since the transformation of theprocess is less, the process is performed more easily.

Referring to FIGS. 6A to 6G, wherein cross-sectional views of theprocess for manufacturing a lower substrate of an LCD device of thepresent embodiment are shown.

A first metal layer (not shown) is first formed on a substrate 601 bysputtering, and a gate 602 in the thin film transistor region A, a lowerelectrode 603 in the auxiliary capacitance region B, and a terminal line604 in the connecting terminal region C are defined. Subsequently, agate insulating layer 605 (SiNx) is formed by PECVD. Then, asemiconductor layer 608 (a-Si) and an ohmic contact layer 622 (n⁺Si) areformed by depositing, and then an active region is defined by coating aphotoresist layer and then by patterning. Subsequently, a second metallayer (not shown) of a Ti/Al/Ti multi-layered structure is formed bysputtering, and the second metal layer is patterned by development andexposure so as to form a source 609 and the drain 610 in the transistorregion A, an upper electrode 611 in the auxiliary capacitance region B,and a connecting line 612 in the connecting terminal region C. TheTi/Al/Ti multi-layered structure of the second metal layer is athree-layered structure so as to avoid etching the second metal layerfor the developer used in the following process. Then, a through hole inthe ohmic contact layer 622 is formed by dry etching, and a passivationlayer 623 (SiNx or SiOx) is formed by chemical vapor deposition, as thestructure shown in FIG. 6A.

Subsequently, a negative photosensitive black resin layer 614 is formingby coating and then by pre-baking. Then, a first negative photosensitiveinsulating layer 613 is formed by coating and then by pre-baking. Asshown in FIG. 6B, a mask is used for performing a photographic step topattern the first negative photosensitive insulating layer 613 and thenegative photosensitive black resin layer 614 to form a region blockinglight. The patterned first negative photosensitive insulating layer 613functions as an overcoat layer of the TFT, and the patterned negativephotosensitive black resin layer 614 functions as the black matrix ofthe TFT.

A negative red filter layer 616 is formed by coating and then bypre-baking. Then, a second negative photosensitive insulating layer 615is formed by coating and then by pre-baking. The negative red filterlayer 616 and the second negative photosensitive insulating layer 615are patterned by exposure and development so as to define a firstcontact hole 617 in the negative red filter layer 616, corresponding tothe drain 610, and a second contact hole 618 in the connecting terminalregion C. Subsequently, a green filter layer 619, a blue filter layer(not shown), and the contact holes thereof (not shown) are defined byrepeating the steps for forming the aforementioned color filter layerand the second photosensitive insulating layer. Each pixel region of thepresent embodiment comprises a color filter layer of one color, and thecolors of the color filter layers neighboring with each other aredifferent. The photosensitive black resin layer and all color filterlayers function as masks to dryly etch the passivation layer 623 in thefirst contact hole 617 corresponding to the drain 610, and thepassivation layer 623 and the gate insulating layer 605 in the secondcontact hole in the connecting terminal region C so as to expose thedrain 610 and the terminal line 604, as shown in FIG. 6C.

Finally, as shown in FIG. 6D, a transparent electrode layer (ITO) 620 isformed, and the pattern of the pixel region is defined by a photographicstep so as to accomplish the process for manufacturing a lower substrateof an LCD device.

The process for manufacturing a lower substrate of an LCD device of thepresent embodiment comprises eight photographic steps, and thetransformation of the process is less. Thereby, the present embodimentreduces the photographic steps by one and the difficulty of the process,in comparison with the conventional process. In addition, a half-tonemask technique can further reduce the photographic steps by one in thepresent embodiment.

Although the present invention has been explained in relation to itspreferred embodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the invention as hereinafter claimed.

1. A method for manufacturing a lower substrate of a liquid crystaldisplay device, comprising: (A) providing a substrate; (B) formingplural transistors individually comprising a gate, a source, and adrain, wherein the gate is disposed on the substrate, at least onesemiconductor layer and at least one gate insulating layer aresandwiched in between the gate and the source/drain, and the drain doesnot electrically connect to the source; (C) forming on the substrate insequence a first photosensitive insulating layer and a black matrix,wherein the first insulating layer and the black matrix are the sametype of photoresist; (D) patterning the first photosensitive insulatinglayer and the black matrix to cover the transistor regions, wherein thepattern of the first photosensitive insulating layer is the same as thatof the black matrix; (E) forming on the substrate in sequence a secondinsulating layer and a color filter layer, wherein the second insulatinglayer and the color filter layer are the same type of photoresist; (F)patterning the second insulating layer and the color filter layer, andsimultaneously forming a first contact hole corresponding to the drain,wherein the first contact layer extends through the second insulatinglayer and the color filter layer so as to expose the part drain; (G)selectively repeating the steps (E) and (F); and (H) forming a patternedtransparent electrode layer on the substrate, which electricallyconnects to the drain.
 2. The method as claimed in claim 1, wherein step(B) further comprises a step for forming plural connecting terminalregions each at least comprising a terminal line on the substrate, andthe gate insulating layer is disposed on the terminal line.
 3. Themethod as claimed in claim 2, wherein step (F) further comprises a stepfor simultaneously forming a second contact hole in the connectingterminal region, and the second contact hole at least extends throughthe second photosensitive insulating layer and the filter layer so as toexpose part of the gate insulating layer.
 4. The method as claimed inclaim 3, further comprising step (G′) between step (G) and step (H),dryly etching the exposed gate insulating layer so as to expose part ofthe terminal line.
 5. The method as claimed in claim 1, wherein step (B)further comprises a step for forming plural connecting terminal regionseach at least comprising a terminal line and a connecting line, theterminal line is disposed on the substrate, the gate insulating layer issandwiched in between the terminal line and the connecting line, and theterminal line connects to the connecting line via a through hole.
 6. Themethod as claimed in claim 5, wherein step (F) further comprises a stepfor forming a second contact hole in the connecting terminal region, andthe second contact hole at least extends through the secondphotosensitive insulating layer and the filter layer so as to exposepart of the connecting line.
 7. The method as claimed in claim 1,wherein step (B) further comprises a step for forming plural auxiliarycapacitance regions each at least comprising a lower electrode, a gateinsulating layer, and an upper electrode, the lower electrode isdisposed on the substrate, and the gate insulating layer is sandwichedin between the upper electrode and the lower electrode.
 8. The method asclaimed in claim 1, wherein the process for patterning the firstphotosensitive insulating layer and the black matrix of step (D) isperformed by a mask, so as to expose and develop the firstphotosensitive insulating layer and the black matrix.
 9. The method asclaimed in claim 1, wherein the process for forming the color filterlayer of step (F) is performed by spin coating.
 10. The method asclaimed in claim 1, wherein the process for forming the color filterlayer of step (F) is performed by ink-jet printing.
 11. The method asclaimed in claim 1, wherein the color of the color filter layercorresponding to one of the transistors is different from that of theneighboring color filter layer corresponding to another of thetransistors.
 12. A method for manufacturing a lower substrate of aliquid crystal display device, comprising: (A) providing a substrate;(B) forming plural transistor regions individually having a gate, asource, and a drain, wherein the gate is disposed on the substrate, atleast one semiconductor layer and at least one gate insulating layer aresandwiched in between the gate and the source/drain, and the drain doesnot electrically connect to the source; (C) forming on the substrate insequence a passivation layer, a black matrix, and a first photosensitiveinsulating layer; (D) patterning the first photosensitive insulatinglayer and the black matrix to cover the transistor regions, wherein thepattern of the first photosensitive insulating layer is the same as thatof the black matrix; (E) forming on the substrate in sequence a secondinsulating layer and a color filter layer; (F) patterning the secondinsulating layer and the color filter layer, and simultaneously forminga first contact hole in the second insulating layer and the color filterlayer on the drain, wherein the first contact hole extends through thesecond insulating layer and the color filter layer so as to expose partof the passivation layer; (G) selectively repeating steps (E) and (F);(H) dryly etching the passivation layer in the first contact hole toexpose part of the drain; and (I) forming a patterned transparentelectrode layer on the substrate, which electrically connects to thedrain.
 13. The method as claimed in claim 12, wherein step (B) furthercomprises a step for forming plural connecting terminal regions each atleast comprising a terminal line on the substrate, and the gateinsulating layer is sandwiched in between the terminal line and thepassivation layer.
 14. The method as claimed in claim 13, wherein step(F) further comprises a step for simultaneously forming a second contacthole in the connecting terminal region, and the second contact holeextends through the second photosensitive insulating layer and the colorfilter layer so as to expose part of the passivation layer.
 15. Themethod as claimed in claim 14, wherein step (H) further comprises a stepfor dryly etching the passivation layer and the gate insulating layer inthe second contact hole so as to expose part of the terminal line. 16.The method as claimed in claim 12, wherein step (B) further comprises astep for forming plural auxiliary capacitance regions each at leastcomprising a lower electrode, a gate insulating layer, and an upperelectrode, the lower electrode is disposed on the substrate, and thegate insulating layer is sandwiched in between the upper electrode andthe lower electrode.
 17. The method as claimed in claim 12, wherein theprocess for patterning the first photosensitive insulating layer and theblack matrix of step (D) is performed by a mask so as to expose anddevelop the first photosensitive insulating layer and the black matrix.18. The method as claimed in claim 12, wherein the process for formingthe color filter layer of step (F) is performed by spin coating.
 19. Themethod as claimed in claim 12, wherein the process for forming the colorfilter layer of step (F) is performed by ink-jet printing.
 20. Themethod as claimed in claim 12, wherein the color of the color filterlayer corresponding to one of the transistor is different from that ofthe neighboring color filter layer corresponding to another of thetransistors.